Which statement best describes LOS and beyond-LOS and their impact on radio planning?

• A. LOS requires satellites; beyond-LOS uses ground relays
• B. LOS is the direct path; beyond-LOS requires relays or higher altitudes; affects frequency choice, power, scheduling
• C. LOS is always longer range than beyond-LOS
• D. Beyond-LOS means you cannot plan any schedule or power adjustments

Answer: (B)

Understanding line-of-sight means you have a direct radio path between your transmitter and the receiver with no major obstructions. In this case, the link budget is governed mainly by free-space path loss, antenna gains, and the transmit power you put into the link. Planning focuses on choosing a frequency and power level that give a reliable margin over the expected distance and terrain, since a clear direct path makes the link straightforward to model.

When the path is beyond-LOS, the direct line cannot be seen because of the Earth’s curvature or obstacles. To communicate, you rely on a relay or a higher vantage point to bridge the gap—this could be a relay tower at altitude or a satellite. Because the signal must hop through an intermediate stage, you have to account for extra losses on each leg, the availability and performance of the relay, and the timing of when that relay can support your link. That’s why planning must consider different frequencies suitable for each segment, possibly higher power to maintain margins across multiple hops, and scheduling to align with relay passes, windows, or duty cycles. These adjustments are essential to maintain a reliable link when you’re nots directly visible to the other end.

In short, direct LOS is a straight path planning scenario, while beyond-LOS requires relays or higher altitude viewpoints and changes how you pick frequencies, set power, and schedule transmissions.